In wired communication networks, terminal devices located in the premises of a customer (also referred to as subscriber) are connected with a central office via communication lines. An example for such a communication network is a public switched telephone network (PSTN). The corresponding telephone services is referred to as plain old telephone service (POTS). In such a case, terminal devices like telephones or facsimile devices, and also data transfer devices are connected with the central office via a pair of copper lines. The copper lines are commonly referred to as tip line and ring line. In the central office, the copper lines are typically connected with a subscriber line interface circuit (SLIC) on a corresponding line card, which in this case is generally referred to as a PSTN (or POTS) line card.
In the central office, a line testing procedure is typically regularly performed, to detect faults (e.g., broken lines) and also to identify if a telephone, a fax, or any other terminal device is connected to the line.
Such line testing is typically performed with dedicated line testing equipment which is coupled to the communication line to be tested, for example via switching elements (e.g., relays). Such dedicated line testing equipment is expensive and requires space. Furthermore, since often only one such dedicated line testing equipment is used for a large number of lines, line testing typically is only performed at larger intervals, for example every seven days.
For these and other reasons, there is a need for the present invention.